1. Field of the Invention
The present invention is directed to a multi-chamber inkjet print head that includes a plurality of individual print head ink chambers that share a common ink filter and are in fluid communication with an ink flow regulator and an associated method of assembling a print head base having at least two separate fluid conduit paths filtered by a single piece of filter.
2. Background of the Invention
The trend in the printer industry is to make higher resolution images at a faster rate. To do this, printer manufacturers are striving to produce prints with more dots per inch, and to develop a better understanding of dot mixing and color matching. In the case of ink jet printers, much of the control comes from the type of spray port that delivers ink to the receiving medium. The spray ports are extremely small holes through which the ink is forced out and onto the paper. The printer manufacturers can alter the type and number of spray ports. Typical ink jet cartridges may have from approximately 30 to 200 spray ports, and the correct operation of the spray port is critical to the proper operation of the printer. It is therefore important to filter out contamination or agglomerations which may be present in the ink prior to the ink reaching the spray ports.
Ink can be forced out the spray ports using a number of different technologies. The ink can be pressed out by a piezoelectric element which expands with a voltage and compresses the ink, creating a pressure to force the ink from a small reservoir. Other methods for forcing the ink through the spray port are referred to as bubble jet and thermal jet techniques.
In ink printer systems, it is important to ensure clean delivery of the ink. If contamination clogs the spray ports, the operation of the ink cartridge is hindered. The flow of ink to the paper may be reduced and/or the plugged ports may drip.
The trend in the industry is to make the diameter of the spray ports even smaller to improve the resolution of the image produced. It has therefore become increasingly more important and difficult to filter out particles that may plug these smaller spray ports.
The most commonly used filter medium is a woven stainless steel screen. These screens can be made with a number of different strands per inch in order to create a pore size for filtration of particles larger than a predetermined size. For example, a screen having 250×1400 strands per inch (98×551 strands per cm) in a double Dutch twill weave, as available from Tetko Inc. will provide filtration for 19 micron nominal diameter and larger particles.
The screens used in these applications are typically stainless steel to ensure chemical compatibility with the ink. In most cases, the ink contains surfactants and/or solvents, as well as other compounds, to promote wetting of the paper or printing substrate. Furthermore, the inks may be acidic or basic.
One problem with stainless steel screens is that they are difficult to bond and seal to ink jet fluid throughputs. The filter material is typically heat staked to the plastic conduits/cavities of the print head base, and because of the irregular edges of the screen, a complete seal is difficult to produce. When cut into disc shapes, the woven screen has ragged edges that, if not sealed properly, can create a leak path for large particles to pass through. In some cases, the stainless steel screen is applied with an adhesive to ensure a good seal. However, this is a time consuming and costly process.
Further, the stainless steel screen can shed loose particles or fibers that can then contaminate or clog the spray ports. When the screen is cut, typically by die cutting, the overlapping metal strands can be pinched and broken. These small screen fragments can shed after the filter disc is adhered to the ink jet cartridge. If one of the shed strands gets downstream of the filter disc, it can clog the spray port head, creating problems with the printer.